In recent years, an information processing amount is increasing, accompanied by development of technology such as a cloud service. In order to process such an enormous amount of information, a calculation amount of a heating element such as a central processing unit (CPU) and a multi-chip module (MCM) tends to increase. Therefore, an amount of heat generation of these heating elements also tends to increase. Accompanied by this tendency, an effort to more efficiently cool a heating element is being carried out every day.
As a cooling technique of a heating element, electronic equipment for cooling a heating element by using a coolant is known (e.g. PTLs 1 and 2).
In a technique described in PTL 1 (Japanese translation of PCT International Application Publication No. 2012-531056), a heating element (a heating electronic device 510) is mounted on a circuit board (a printed circuit board 540). A housing (a module casing 530, an uppermost wall 571 of a housing) accommodates the heating element, and is mounted on one surface of the circuit board in such a way as to seal a coolant (a dielectric cooling liquid 532) with respect to the one surface of the circuit board.
Further, two pumps (impingement cooling type immersible pumps 535 and 536) are disposed in the coolant within the housing and circulate the coolant. Further, a cooling mechanism (a liquid cooling cold plate 420) is mounted on an upper surface of the housing (the uppermost wall 571 of the housing). In the cooling mechanism, a coolant different from the coolant within the housing flows from a suction port toward a discharge port.
In this way, in the technique described in PTL 1, the heating element is cooled by circulating the coolant in the housing, and flowing a coolant different from the coolant in the housing within the cooling mechanism.
In a technique described in PTL 2 (Japanese Unexamined Patent Application Publication No. S59-188198), at least a part of a heating component is incorporated in an electronic circuit package. Further, a cover is formed in such a way that a sealing container in which the cover serves as a part of a wall of a component mounting surface of the package is constituted, and the heating component is immersed by injecting a cooling liquid into the cover.
Note that a technique related to the present invention is also disclosed in PTL 3 (Japanese Unexamined Patent Application Publication No. 2013-187251).
However, in the techniques described in PTLs 1 and 2, a housing is mounted on one surface of a circuit board in such a way that a heating element is accommodated and a coolant is sealed with respect to the one surface of the circuit board. Specifically, a coolant and a heating element are sealed in a space surrounded by one surface of a circuit board and a housing. When a temperature of a heating element increases, an inner pressure of the above-described sealed space increases, and deformation such as deflection may occur in the circuit board. When the deformation increases, there occurs a problem that a wiring formed on the circuit board may be cut, a gap may be formed in a connection portion between the circuit board and the housing, thereby causing leakage of a coolant, or the like.